Which of the following situations can be approximated to a steady state heat transfer system? (A) A red hot steel slab (having outside surface temperature as 1300°C) exposed to the atmospheric air at 35°C (B) 10 kg of dry saturated steam at 8 kgf/cm2 flowing through a short length of stainless steel pipe exposed to atmospheric air at 35°C (C) Boiling brine kept in open vessel when the bottom surface temperature of the vessel is maintained constant at 180°C (D) A sub-cooled refrigerant liquid at 8°C flowing at the rate of 6 Kg/minute through a copper pipe exposed to atmospheric air at 35°C

Which of the following situations can be approximated to a steady state
heat transfer system?
(A) A red hot steel slab (having outside surface temperature as 1300°C)
exposed to the atmospheric air at 35°C
(B) 10 kg of dry saturated steam at 8 kgf/cm2
flowing through a short length
of stainless steel pipe exposed to atmospheric air at 35°C
(C) Boiling brine kept in open vessel when the bottom surface temperature of
the vessel is maintained constant at 180°C
(D) A sub-cooled refrigerant liquid at 8°C flowing at the rate of 6 Kg/minute
through a copper pipe exposed to atmospheric air at 35°C
by

1 Answer

Answer :

(B) 10 kg of dry saturated steam at 8 kgf/cm2
flowing through a short length
of stainless steel pipe exposed to atmospheric air at 35°C
by

Related questions

The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the right face is 10 W/m2 .K. At steady state, the temperature of the right face in °C is (A) 77.2 (B) 71.2 (C) 63.8 (D) 48.7

Description : The left face of a one dimensional slab of thickness 0.2 m is maintained at 80°C and the right face is exposed to air at 30°C. The thermal conductivity of the slab is 1.2 W/m.K and the heat transfer co-efficient from the ... temperature of the right face in °C is (A) 77.2 (B) 71.2 (C) 63.8 (D) 48.7

Last Answer : (D) 48.7

Unsaturated air (with dry bulb temperature and dew point being 35°C and 18°C respectively) is passed through a water spray chamber maintained at 15°C. The air will be cooled (A) And humidified (B) And dehumidified with increase in wet bulb temperature (C) At the same relative humidity (D) And dehumidified with decrease in wet bulb temperature

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Last Answer : (D) And dehumidified with decrease in wet bulb temperature

Temperature and gage pressure maintained during the manufacture of hot SBR (styrene butadiene rubber) are (A) 50°C and 3 - 4 kg/cm2 (B) 50°C and 1 kgf/cm2 (C) 250°C and 10 kgf/cm2 (D) 250°C and 1 kgf/cm

Description : Temperature and gage pressure maintained during the manufacture of hot SBR (styrene butadiene rubber) are (A) 50°C and 3 - 4 kg/cm2 (B) 50°C and 1 kgf/cm2 (C) 250°C and 10 kgf/cm2 (D) 250°C and 1 kgf/cm

Last Answer : (A) 50°C and 3 - 4 kg/cm

Unsaturated air (with dry and wet bulb temperatures being 35 and 25°C respectively) is passed through water spray chamber maintained at 35°C. The air will be (A) Cooled (B) Humidified (C) Both (A) & (B) (D) Dehumidified

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Last Answer : (B) Humidified

Boiling of milk in an open vessel is an example of __________ boiling. (A) Film (B) Sub-cooled (C) Saturated nucleate (D) None of these

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Last Answer : (A) Film

n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In each batch about 120 kgs of material is dried. a. The quantity of moisture removed per batch. b. What is the total quantity ( sensible & latent) of heat required to evaporate the moisture, if the latent heat of water is 540 kcal/kg at atmospheric conditions, Ignore heat absorbed by the solids c. Find the quantity of steam required for the drying process (per batch), if steam at 4 kg/cm2 is used for generating hot air in the dryer and the dryer efficiency is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.

Description : n a chemical factory where dyes are made, wet cake at 30 OC consisting of 60% moisture  is put in a dryer to obtain an output having only 5% moisture, at atmospheric pressure. In  each batch about 120 ... dryer and the dryer efficiency  is 80%. Latent heat of steam at 4 kg/cm2 is 520 kcal/kg.

Last Answer : Given that   Qty of material dried per batch - 120 Kgs  Moisture at inlet - 60% a. The quantity of moisture removed per batch.  Water quantity in a wet batch - 120 x 0.6 = 72 Kgs.  Quantity of bone dry ... - 48/0.95 = 50.5 Kgs.  Equivalent water in a dry batch - 50.5 - 48 = 2.5 Kgs.

In a vapour compression cycle, the refrigerant immediately after expansion valve is (a) liquid (b) sub-cooled liquid (c) saturated liquid (d) wet vapour

Description : In a vapour compression cycle, the refrigerant immediately after expansion valve is (a) liquid (b) sub-cooled liquid (c) saturated liquid (d) wet vapour

Last Answer : Ans: d

__________________ is a liquid at the saturations which has temperature equal to the boiling point corresponding to the existing pressure.  a. Saturation Temperature  b. Sub cooled Liquid  c. Compressed Liquid  d. Saturated Liquid

Description : __________________ is a liquid at the saturations which has temperature equal to the boiling point corresponding to the existing pressure.  a. Saturation Temperature  b. Sub cooled Liquid  c. Compressed Liquid  d. Saturated Liquid

Last Answer : Saturated Liquid

Heat transfer in the laminar sub-layer in case of a liquid flowing through a pipe, is mostly by (A) Eddies current (B) Conduction (C) Convection (D) None of these

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Last Answer : (B) Conduction

In a constant pressure process steam is generated from 10 bar and 0.8 dry condition till it become dry and saturated. Determine amount of heat added per kg of steam. From steam table at 10 bar Tsat = 179.9°C hf = 762.6 kl/kg, hg = 2776.2 kJ/kg

Description : In a constant pressure process steam is generated from 10 bar and 0.8 dry condition till it become dry and saturated. Determine amount of heat added per kg of steam. From steam table at 10 bar Tsat = 179.9°C hf = 762.6 kl/kg, hg = 2776.2 kJ/kg 

Last Answer : Constant pressure process Final condition of steam is dry saturated Enthalpy of dry steam = hg= hf + hfg =2776.2 KJ/Kg .Given Latent heat of vaporization = hfg = hg - hf =2776.2-762.6 =2013.6 KJ/Kg Initial condition ... hfg = 762.6+0.8 X 2013.6 =2373.48 KJ/Kg Heat added = hg-hw = 402.72 KJ/kg

At equilibrium the concentration of water in vapour phase (C* ) in kg/m3 of air space and the amount of water (m) adsorbed per kg of dry silica gel are related by, C* = 0.0667m. To maintain dry conditions in a room of air space 100m3 containing 2.2 kg of water vapour initially, 10 kg of dry silica gel is kept in the room. The fraction of initial water remaining in the air space after a long time (during which the temperature is maintained constant) is (A) 0.0 (B) 0.2 (C) 0.4 (D) 1.0

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Last Answer : (C) 0.4

Leidenfrost point is a term concerned with the (A) Condensation of the saturated vapor on a cold surface (B) Concentration of a corrosive solution by evaporation (C) Heat transfer between two highly viscous liquids (D) Boiling of a liquid on a hot surface

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Last Answer : (D) Boiling of a liquid on a hot surface

An ideal liquid refrigerant should (A) Not have a sub-atmospheric vapour pressure at the temperature in the refrigerator coils (B) Not have unduly high vapour pressure at the condenser temperature (C) Both (A) and (B) (D) Have low specific heat

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Last Answer : (C) Both (A) and (B)

Temperature and gage pressure maintained during the manufacture of cold SBR (styrene butadiene rubber) are (A) 5°C and 1 kgf/cm2 (B) - 20°C and 1 kgf/cm2 (C) 0°C and 1 kgf/cm2 (D) 0°C and 3 kgf/cm

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Last Answer : (A) 5°C and 1 kgf/cm

Unsaturated air (with dry bulb and wet bulb temperatures being 45°C and 25°C respectively) is passed through a water spray chamber maintained at 23°C. The air will be cooled and (A) Humidified with wet bulb temperature decreasingB) Humidified at constant wet bulb temperature(C) Dehumidified(D) None of these

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Last Answer : (A) Humidified with wet bulb temperature decreasing

In case of unsteady fluid flow, conditions & flow pattern change with the passage of time at a position in a flow situation. Which of the following is an example of unsteady flow? (A) Discharge of water by a centrifugal pump being run at a constant rpm (B) Water flow in the suction and discharge pipe of a reciprocating pump (C) Water discharge from a vertical vessel in which constant level is maintained (D) Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe

Description : In case of unsteady fluid flow, conditions & flow pattern change with the passage of time at a position in a flow situation. Which of the following is an example of unsteady flow? (A) ... level is maintained (D) Low velocity flow of a highly viscous liquid through a hydraulically smooth pipe

Last Answer : (B) Water flow in the suction and discharge pipe of a reciprocating pump

Choose the wrong statement (a) Temperature of medium being cooled must be below that of the evaporator (b) Refrigerant leaves the condenser as liquid (c) All solar thermally operated absorption systems are capable only of intermittent operation (d) frost on evaporator reduces heat transfer

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Last Answer : Ans: a

A 10m^3 vessel initially contains 5 m^3 of liquid water and 5 m^3 of saturated water vapor at 100 kPa. Calculate the internal energy of the system using the steam table.  A. 5 x10^5 kJ  B. 8x10^5 kJ  C. 1 x10^6 kJ  D. 2 x10^6 kJ Formula: fromthe steamtable vƒ = 0.001043 m^3 / kg vg = 1.6940 m^3 / kg u ƒ= 417.3 kJ/kg ug= 2506kJ/kg formula: Mvap = V vap/vg M liq = Vliq/ vƒ u =uƒM liq + ug M vap

Description : A 10m^3 vessel initially contains 5 m^3 of liquid water and 5 m^3 of saturated water vapor at 100 kPa. Calculate the internal energy of the system using the steam table.  A. 5 x10^5 kJ  B. 8x10^5 kJ  C. 1 ... 3 kJ/kg ug= 2506kJ/kg formula: Mvap = V vap/vg M liq = Vliq/ vƒ u =uƒM liq + ug M vap

Last Answer : 2 x10^6 kJ

__________ is the temperature at which a gas-vapor mixture becomes saturated, when cooled at constant total pressure out of contact with a liquid. (A) Dew point (B) Bubble point (C) Dry bulb temperature (D) Wet bulb temperature

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Last Answer : (A) Dew point

In sub-cooled boiling, (A) Temperature of the heating surface is less than the boiling point of the liquid (B) Temperature of the heating surface is more than the boiling point of the liquid (C) Bubbles from heating surface are absorbed by the mass of the liquid (D) Very large vapour space is necessary

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Last Answer : (B) Temperature of the heating surface is more than the boiling point of the liquid

Stainless steel is not corroded by (A) Hydrochloric acid (10%) (B) Nitric acid (10%) (C) Sulphuric acid (10%) (D) Saturated brine

Description : Stainless steel is not corroded by (A) Hydrochloric acid (10%) (B) Nitric acid (10%) (C) Sulphuric acid (10%) (D) Saturated brine

Last Answer : (B) Nitric acid (10%)

Though increased pressure has a retarding effect on cracking reaction, yet in actual process, a positive pressure of 10-15 kgf/cm2 is maintained during cracking mainly to (A) Increase the yield of light distillates (B) Suppress coke formation (C) Enhance the octane number of gasoline (D) Reduce gum content in gasoline

Description : Though increased pressure has a retarding effect on cracking reaction, yet in actual process, a positive pressure of 10-15 kgf/cm2 is maintained during cracking mainly to (A) Increase the yield of ... coke formation (C) Enhance the octane number of gasoline (D) Reduce gum content in gasoline

Last Answer : (B) Suppress coke formation

Heat flux increases with temperature drop beyond the Leiden frost point in the plot of heat flux vs. temperature drop for a boiling liquid, because (A) Convection becomes important (B) Conduction becomes important (C) Radiation becomes important (D) Sub-cooled boiling occurs

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Pick out the wrong statement. (A) Economy of a multiple effect evaporator is not influenced by the boiling point elevation (B) Two identical cubes of iron and copper will have the same heat content under the same conditions of temperature (C) Double pipe heat exchangers are mostly used in the field of refrigeration (D) Finned tube heat exchangers are suitable for heating air by steam

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Last Answer : (B) Two identical cubes of iron and copper will have the same heat content under the same conditions of temperature

Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans? (A) Emissivity of pipe surface (B) Diameter & length of the pipe (C) Temperature of hot pipe surface & that of air in the room (D) None of thes

Description : Which of the following parameters is not responsible for the heat loss from a hot steam carrying bare pipe surface located in a room without fans? (A) Emissivity of pipe surface (B) Diameter & length of the pipe (C) Temperature of hot pipe surface & that of air in the room (D) None of thes

Last Answer : Option D

Vinyl chloride (CH2 = CH.Cl) is produced by the thermal pyrolysis of ethylene dichloride at a pressure & temperature of (A) 4 kgf/cm2 & 500°C (B) 10 kgf/cm2 & 1000°C (C) 40 kg/cm2 & 200°C (D) 100 kgf/cm2 & 500°C

Description : Vinyl chloride (CH2 = CH.Cl) is produced by the thermal pyrolysis of ethylene dichloride at a pressure & temperature of (A) 4 kgf/cm2 & 500°C (B) 10 kgf/cm2 & 1000°C (C) 40 kg/cm2 & 200°C (D) 100 kgf/cm2 & 500°C

Last Answer : (A) 4 kgf/cm2 & 500°C

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Last Answer : Option A

Temperature of hot gases flowing in a pipe is measured by a thermocouple inserted in the thermal well. The thermal well made of __________ will facilitate the most accurate measurement of the temperature. (A) Copper (B) Steel (C) Aluminium (D) Brass

Description : Temperature of hot gases flowing in a pipe is measured by a thermocouple inserted in the thermal well. The thermal well made of __________ will facilitate the most accurate measurement of the temperature. (A) Copper (B) Steel (C) Aluminium (D) Brass

Last Answer : Option A

A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid. (A) Sub-cooled (B) Saturated (C) Non-solidifiable (D) None of these

Description : A liquid under pressure greater than its vapour pressure for the temperature involved is called a __________ liquid. (A) Sub-cooled (B) Saturated (C) Non-solidifiable (D) None of these

Last Answer : (A) Sub-cooled

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Last Answer : (B) Saturated wate

The main problem with such a heat treatment of stainless steel pipe spools and the reason why it is not regularly employed is: a) Controlling the rate of the temperature rise b) Controlling the cooling c) The length of the soak period d) High risk of distortion

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Last Answer : d) High risk of distortion

Which of the following is the most suitable material of construction for the condenser tubes, where the cooling medium is brine (salty water)? (A) Aluminium (B) Copper (C) Titanium (D) Stainless steel

Description : Which of the following is the most suitable material of construction for the condenser tubes, where the cooling medium is brine (salty water)? (A) Aluminium (B) Copper (C) Titanium (D) Stainless steel

Last Answer : Option C

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Last Answer : Compressed Liquid

________________ is one which has a temperature lower than the saturation temperature corresponding to the existing pressure.  a. Saturation Temperature  b. Sub cooled Liquid  c. Compressed Liquid  d. Saturated Liquid

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Last Answer : Sub cooled Liquid

______________ is the temperature at which liquids start to boil or the temperature at which vapors begin to condense.  a. Saturation Temperature  b. Sub cooled Liquid  c. Compressed Liquid  d. Saturated Liquid

Description : ______________ is the temperature at which liquids start to boil or the temperature at which vapors begin to condense.  a. Saturation Temperature  b. Sub cooled Liquid  c. Compressed Liquid  d. Saturated Liquid

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Pick out the wrong statement. (A) The controlling resistance in case of heating of air by condensing steam is in the air film (B) The log mean temperature difference (LMTD) for counter flow and parallel flow can be theoretically same when any one of the fluids (hot or cold fluid) passes through the heat exchanger at constant temperature (C) In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply, when a temperature cross occurs (D) Phase change in case of a pure fluid at a given pressure from liquid to vapor or vice-versa occurs at saturation temperature

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Last Answer : (C) In case of a 1 - 2 shell and tube heat exchanger, the LMTD correction factor value increases sharply, when a temperature cross occurs

Choose the correct statement (a) A refrigerant should have low latent heat (b) If operating temperature of system is low, then refrigerant with low boiling point should be used (c) Pre-cooling and sub-cooling bf refrigerant are same (d) Superheat and sensible heat of a. refrigerant are same

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Last Answer : Ans: b

Heat transfer by conduction in the turbulent core of a fluid flowing through a heated pipe is negligible, if the value of Prandtl number is (A) 0.2 (B) 0.4 (C) 0.6 (D) 0.8

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Last Answer : (C) 0.6

A certain refrigerating system has a normal operating suction pressure of 10 kg/cm gauge and condensing pressure ofabout 67 kg/cm. The refrigerant used is (a) Ammonia (b) Carbon dioxide (c) Freon (d) Brine

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Last Answer : Ans: b

Melting point & boiling points of liquid oxygen are respectively - 218.8°C & - 183°C, while the same for liquid nitrogen is - 210°C & - 195.8°C respectively. The difference in melting points of liquid oxygen & liquid nitrogen is not equal to 8.8 (A) °C (B) °F (C) °K (D) °R

Description : Melting point & boiling points of liquid oxygen are respectively - 218.8°C & - 183°C, while the same for liquid nitrogen is - 210°C & - 195.8°C respectively. The difference in melting points of liquid oxygen & liquid nitrogen is not equal to 8.8 (A) °C (B) °F (C) °K (D) °R

Last Answer : (B) °F

A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place (A) The better insulation material should be put just next to pipe (i.e., inside) (B) The better insulating material should be put outside (C) Either of the insulating material could be put on either side (D) Steam temperature is considered before deciding as to which insulating material is to be put inside (i.e., just next to the pipe)

Description : A steam pipe is intended to be insulated with two layers of insulating materials of different thermal conductivities. For minimum heat transfer to take place (A) The better insulation material should be put just ... to which insulating material is to be put inside (i.e., just next to the pipe)

Last Answer : (A) The better insulation material should be put just next to pipe (i.e., inside)

Double pipe heat exchangers are preferably useful, when (A) High viscosity liquid is to be cooled (B) Requirement of heat transfer area is low (C) Overall heat transfer co-efficient is very high (D) A corrosive liquid is to be heated

Description : Double pipe heat exchangers are preferably useful, when (A) High viscosity liquid is to be cooled (B) Requirement of heat transfer area is low (C) Overall heat transfer co-efficient is very high (D) A corrosive liquid is to be heated

Last Answer : (B) Requirement of heat transfer area is low

A thin, flat & square plate measuring 2 m × 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will remain constant at 30°C, if the convective heat transfer co-efficient is __________ W/m2 °C. (A) 50 (B) 100 (C) 150 (D) 200

Description : A thin, flat & square plate measuring 2 m 2 m is freely hanging in ambient air at 25°C. It is exposed to the solar radiation falling on one side of the plate at the rate of 500 W/m2. The plate temperature will ... heat transfer co-efficient is __________ W/m2 °C. (A) 50 (B) 100 (C) 150 (D) 200

Last Answer : (B) 100

One barometric pressure or 1 atmospheric pressure is equal to  (a) 1 kgf/cnr2  (b) 1.033 kgf/cm2  (c) 0 kgf/cm2  (d) 1.0197 kgf/cm2  (e) 100 kgf/cm2.

Description : One barometric pressure or 1 atmospheric pressure is equal to  (a) 1 kgf/cnr2  (b) 1.033 kgf/cm2  (c) 0 kgf/cm2  (d) 1.0197 kgf/cm2  (e) 100 kgf/cm2.

Last Answer : Answer : b

The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C

Description : The heat flux (from outside to inside) across an insulating wall with thermal conductivity, K = 0.04 W/m.°K and thickness 0.16m is 10 W/m2 . The temperature of the inside wall is - 5°C. The outside wall temperature is (A) 25°C (B) 30°C (C) 35°C (D) 40°C

Last Answer : (C) 35°C

A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co￾efficient for turbulent flow conditions is proportional to (A) d 0.8 (B) d -0.2 (C) d -1 (D) d -1.8

Description : A fluid is flowing inside the inner tube of a double pipe heat exchanger with diameter 'd'. For a fixed mass flow rate, the tube side heat transfer co￾efficient for turbulent flow conditions is proportional to (A) d 0.8 (B) d -0.2 (C) d -1 (D) d -1.8

Last Answer : (B) d -0.2

The flow of a liquid through tapering pipe at a constant rate is an example of __________ flow. (A) Steady uniform (B) Steady non uniform (C) Unsteady uniform

Description : The flow of a liquid through tapering pipe at a constant rate is an example of __________ flow. (A) Steady uniform (B) Steady non uniform (C) Unsteady uniform

Last Answer : (B) Steady non uniform

A process stream of dilute aqueous solution flowing at the rate of10 Kg.s -1 is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 Kg.s -1 . A 1 - 1 shell and tube heat exchanger is available. The best arrangement is (A) Counter flow with process stream on shell side (B) Counter flow with process stream on tube side (C) Parallel flow with process stream on shell side (D) Parallel flow with process stream on tube side

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Last Answer : (A) Counter flow with process stream on shell side